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• Geo(vgicaC7echnics Inc. 0 Page 2 Feasibility Study Work Plan—Appendix E ProjectNo.425.2 August 17,2000 ' the perforated segments (0.040 inch slots) of pipe, then placing excavated fill dirt on top of the filter pack and around the blank sections of the pipe (Figure 3). The piping will consist of ' 3 inch diameter schedule 40 PVC piping with glued bell joints. Once completed, the trenches will be compacted and recapped with asphalt to prevent short-circuiting of the vapor extraction system. 2.3 Proposed Air Sparging Wells We propose to be installed up to 10 air-sparg wells on site to address the groundwater contamination. However, please note that changes will likely be made after the pilot test is ' complete. The soil vapor extraction trenches will recover the air injected into the aquifer and resultant volatilized hydrocarbons and the emissions treated by the thermal oxidizer. Air sparging will begin once field evidence suggests that soil vapor extraction has removed the ' floating product from on top of the water table. V&W will advance the air sparging borings to 40 below ground surface using drive core drilling methods. The air sparging wells will be completed with 1 inch diameter schedule 40 PVC pipe with a screened interval (0.010 inch slots) extending from 38 to 40 feet surrounded by a #2 sand. A granular bentonite transition seal will be completed above the sand filter ' pack and the remaining annulus will be pressure grouted to surface using a <4% bentonite cement grout. 2.4 Soil Vapor Extraction System Soil vapor will be extracted from the VETs using a positive displacement blower. The ' horsepower requirements and vacuum pressure desired will be determined after the pilot test. Soil vapor will pass through a filter to protect the blower against wear from sediment particles. Entrained water will be removed and collected using a baffled water knock out ' drum. Automatic level controls will pump recovered condensate from the knock out drum into DOT approved drums. The drums will be labeled and stored on site inside of the fenced enclosure. The water will be disposed of by a licensed petroleum recycling company or by ' on-site treatment using the remedial system. A system of underground schedule 40 PVC pipes will connect individual vapor extraction ' trench systems to a manifold. The manifold will allow discrete airflow and vacuum pressure control to each vapor extraction trench. The vapor extraction manifold will be easily configured and will be located within the secured treatment compound. ' 2.5 Emissions Treatment System ' Initially the emissions will be treated using coal based granular activated carbon. Two 1,000 lb. carbon units will be connected in series and monitored individually on a graduated scale starting on a weekly basis then moving to a bi-monthly and then a monthly basis. 1